<?php
/**
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; under version 2
 * of the License (non-upgradable).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (c) 2008-2010 (original work) Deutsche Institut für Internationale Pädagogische Forschung (under the project TAO-TRANSFER);
 *               2009-2012 (update and modification) Public Research Centre Henri Tudor (under the project TAO-SUSTAIN & TAO-DEV);
 *
 */

/**
 * Short description of class tao_helpers_translation_RDFExtractor
 *
 * @access public
 * @author Joel Bout, <joel.bout@tudor.lu>
 * @package tao

 */
class tao_helpers_translation_RDFExtractor extends tao_helpers_translation_TranslationExtractor
{
    // --- ASSOCIATIONS ---


    // --- ATTRIBUTES ---

    /**
     * Short description of attribute translatableProperties
     *
     * @access private
     * @var array
     */
    private $translatableProperties = [];

    /**
     * Short description of attribute xmlBase
     *
     * @access private
     * @var array
     */
    private $xmlBase = [];

    // --- OPERATIONS ---

    /**
     * Short description of method extract
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @return mixed
     */
    public function extract()
    {
        
        foreach ($this->getPaths() as $path) {
            // In the RDFExtractor, we expect the paths to points directly to the file.
            if (!file_exists($path)) {
                throw new tao_helpers_translation_TranslationException("No RDF file to parse at '${path}'.");
            } elseif (!is_readable($path)) {
                throw new tao_helpers_translation_TranslationException("'${path}' is not readable. Please check file system rights.");
            } else {
                try {
                    $tus = [];
                    $rdfNS = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
                    $rdfsNS = 'http://www.w3.org/2000/01/rdf-schema#';
                    $xmlNS = 'http://www.w3.org/XML/1998/namespace'; // http://www.w3.org/TR/REC-xml-names/#NT-NCName
                    
                    $translatableProperties = $this->translatableProperties;
                    
                    // Try to parse the file as a DOMDocument.
                    $doc = new DOMDocument('1.0', 'UTF-8');
                    $doc->load(realpath($path));
                    if ($doc->documentElement->hasAttributeNS($xmlNS, 'base')) {
                        $this->xmlBase[$path] = $doc->documentElement->getAttributeNodeNS($xmlNS, 'base')->value;
                    }
                    
                    $descriptions = $doc->getElementsByTagNameNS($rdfNS, 'Description');
                    foreach ($descriptions as $description) {
                        if ($description->hasAttributeNS($rdfNS, 'about')) {
                            $about = $description->getAttributeNodeNS($rdfNS, 'about')->value;
                            
                            // At the moment only get rdfs:label and rdfs:comment
                            // c.f. array $translatableProperties
                            // In the future, this should be configured in the constructor
                            // or by methods.
                            $children = [];
                            foreach ($translatableProperties as $prop) {
                                $uri = explode('#', $prop);
                                if (count($uri) == 2) {
                                    $uri[0] .= '#';
                                    $nodeList = $description->getElementsByTagNameNS($uri[0], $uri[1]);
                                    
                                    for ($i = 0; $i < $nodeList->length; $i++) {
                                        $children[] = $nodeList->item($i);
                                    }
                                }
                            }
                            
                            foreach ($children as $child) {
                                // Only process if it has a language attribute.
                                $tus = $this->processUnit($child, $xmlNS, $about, $tus);
                            }
                        } else {
                            // Description about nothing.
                            continue;
                        }
                    }
                    
                    $this->setTranslationUnits($tus);
                } catch (DOMException $e) {
                    throw new tao_helpers_translation_TranslationException("Unable to parse RDF file at '${path}'. DOM returns '" . $e->getMessage() . "'.");
                }
            }
        }
    }

    /**
     * Short description of method addTranslatableProperty
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @param  string propertyUri
     * @return mixed
     */
    public function addTranslatableProperty($propertyUri)
    {
        
        $this->translatableProperties[] = $propertyUri;
    }

    /**
     * Short description of method removeTranslatableProperty
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @param  string propertyUri
     * @return mixed
     */
    public function removeTranslatableProperty($propertyUri)
    {
        
        foreach ($this->translatableProperties as $prop) {
            if ($prop == $propertyUri) {
                unset($prop);
            }
        }
    }

    /**
     * Short description of method setTranslatableProperties
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @param  array propertyUris
     * @return mixed
     */
    public function setTranslatableProperties($propertyUris)
    {
        
        $this->translatableProperties = $propertyUris;
    }

    /**
     * Short description of method getXmlBase
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @param  string path
     * @return string
     */
    public function getXmlBase($path)
    {
        $returnValue = (string) '';

        
        if (!isset($this->xmlBase[$path])) {
            throw new tao_helpers_translation_TranslationException('Missing xmlBase for file ' . $path);
        }
        $returnValue = $this->xmlBase[$path];
        

        return (string) $returnValue;
    }

    /**
     * @param $child
     * @param $xmlNS
     * @param $about
     * @param $tus
     * @return array
     */
    protected function processUnit($child, $xmlNS, $about, $tus)
    {
        if ($child->hasAttributeNS($xmlNS, 'lang')) {
            $sourceLanguage = 'en-US';
            $targetLanguage = $child->getAttributeNodeNS($xmlNS, 'lang')->value;
            $source = $child->nodeValue;
            $target = $child->nodeValue;

            $tu = new tao_helpers_translation_RDFTranslationUnit();
            $tu->setSource($source);
            $tu->setTarget($target);
            $tu->setSourceLanguage($sourceLanguage);
            $tu->setTargetLanguage($targetLanguage);
            $tu->setSubject($about);
            $tu->setPredicate($child->namespaceURI . $child->localName);

            $tus[] = $tu;
            return $tus;
        }
        return $tus;
    }
}